The influence of hail net on the water balance and leaf pigment content of apple orchards

Apple production accounts for 60–65 % of all fruit production in Hungary, as one of the most important areas of the fruit production sector. Extreme weather conditions in the continental climate can cause significant problems in apple production. The most important solutions to decrease their effects are irrigation and hail net. In addition to protection against hail damage, the hail net has effect on microclimatic factors, its shading effect has a positive effect on the growth of fruit trees and it reduces the risk of sunburn and transpiration. The aim of our research was to evaluate the effect of hail net on the water balance of Early Gold and Golden Reinders microclimatic factors on the basis of thermal imaging, water potential measurement, canopy dry matter content and to analyze the effect on pigment content. The research was carried out on a weekly basis in July and August 2019 at the Horticultural Unit of Pallag, University of Debrecen, Hungary. Based on our results, the air temperature was 2.91 % lower (p = 0.150) and the relative humidity was 3.16 % higher (p = 0.0001) under the hail net. Results also revealed that the foliage temperature was 7.28 % lower (p = 0.006), the water potential value of the foliage was 20.80 % higher (p = 0.399) under the hail net, while the dry matter content of the leaf was 4.76 % lower than in orchards outside the hail net. Canopy chlorophyll concentration was 10.24 % (p = 0.066) higher and carotenoid values were also higher (16.24 %, p = 0.004) in hail net protected circumstances. Based on the results, the hail net has a favorable effect on the water balance of apple orchards and pigment content of apple leaves through microclimatic conditions, partially offsetting the negative effects caused by summer heat and drought stress.